3/15/2010 1 ES 422 Qualitative Biomechanical Analysis for Improving Technique Topics y Types of Biomechanical Analysis y Processes of Qualitative Biomechanical Analysis y Example Qualitative analysis y Qualitative analysis is defined ?as the systematic observation and introspective judgment of the quality of human movement for the purpose of providing the most appropriate intervention to improve performance? (Knudson and Morrison, 2002). 3/15/2010 2 Qualitative vs Quantitative y Subjective nature y Continuum of movement analysis Qualitative Quantitative Developmental level Rating scale Stride length, freq Velocity, Acceleration, force Topics y Types of Biomechanical Analysis y Processes of Qualitative Biomechanical Analysis y Example An Integrated Model Preparation Observation Evaluation/ diagnosis Instruction 3/15/2010 3 Preparation y Knowledge of activity y Knowledge of performers y Relevant systematic observational strategies Preparation: Knowledge of Activity y Description of an ideal technique y Source of information y EiExperience y Expert opinion y Scientific research Preparation: Knowledge of Activity y Goal/purpose y Objective/mechanical y Distance/height y Time y Non-objective y Scores of game y Judge scores 3/15/2010 4 Preparation: Knowledge of Activity y Critical characteristics y Parts of movements can be least modified (Arend & Higgins 1976) y Identify critical features y Develop a deterministic model y Knowledge of activity y Knowledge of biomechanics y Common sense Identify critical features y Two methods y Observe elite performance many times, and identify key features y Te a c h i n g materials: common actions and positionsgp 3/15/2010 5 Identify critical characteristics y Break the purpose into different parts y Long jump: achieve longest jump distance (L) y L = L1 + L2 + L3 y Where y L1: takeoff distance y L2: flight distance y L3: landing distance (Hay, 1993) Identify critical characteristics y High jump: clear the bar height y H b = h 1 + h 2 -h 3 y Where y h 1 : body COG height at takeoff y h 2 : max vertical displacement of COG from takeoff y h 3 : the difference of the max jumping height and the jumper?s COG vertical position Deterministic model: Long jump mechanical model Distance Takeoff distance (L1) Flight distance (L2) Landing distance (L3) Body position at takeoff Initial body position Change in body position Takeoff speed Take angle Relative height of takeoff Ari resistance Body position at touchdown Actions after touchdown (Hay 1983) 22 sin cos 2 x yr vvvgh D g ??++ = 3/15/2010 6 Biomechanical Principles y Summation of joint torques y Continuity of joint torques y Impulse y Summation and continuity of segment velocities y Generation of angular momentum y Cti f l y Reaction y Equilibrium Conservation of angu ar momentum y Manipulation of moment of inertia y Manipulation of segment angular momentum (Norman, 1975) Observation y Careful planning needed y Who?: skill levels y Elite y Novice y What conditions? y Game situations y Class or practices y Simulated situation y With minimal distraction Observation y Where to observe? y The vintage point y Major plane of movement y Distance view y Closer-up view y Multiple viewing positions Approaching: 3/15/2010 7 Observation y Multiple planes of movements y Primary plane vs secondary plane(s) y Videotaping Observation y What to look for? y Whole body or a body segment at a particular instance y Duration and range of motion of the body and its segments y Velocity and acceleration of body segments/joints y Timing of the motion (sequence) of the body segments/joints Observation y Use other senses y Sound can reveal what sight can not reveal in some cases y Sound of contact between hand and volleyball: proper contact y Touch 3/15/2010 8 Evaluation y Identify errors: two steps y Identify errors comparing with ideal performance D h ff f f y etermine the e ects o errors on per ormance Evaluation y Evaluate errors y Error correction y Causes and effects y Some considerations y Does the error expose the student to the danger of injury? y Who are your clients? y How easy is it to correct the errors? y Is the error a result of an earlier error in the movement sequence? y How great an effect does the error on the performance? y Are the deficiencies due to the poorly designed equipment or inappropriate equipment? Evaluation y Rank the errors y From major to minor errors - effect on performance y From earliest to latest errors - in their sequence of occurrence y From easiest to hardest errors to correct y Those errors ranked near the bottom of the list should ignored or attended last 3/15/2010 9 Instruction/Feedback y Communicate with the performer effectively: what they did wrong and what you what them to be y Ve rb a l y Demonstration h y Correct the error y Break the movement into parts y Devise drills to correct the error in each part y Slow to fast y Repeat the analysis Topics y Types of Biomechanical Analysis y Processes of Qualitative Biomechanical Analysis y Example Example y Forehand drive in tennis y Description of the skill: y Knowledge y Purpose y Develop a model y Racket to court time y Path of ball 3/15/2010 10 Deterministic model Winner Racket-to-court time Horizontal distance to baseline Path of ball Horizontal velocity of ball after impact Friction b/n ball & court Air resistance Ball height Vertical velocity of ball after impact Player position on court Horizontal velocity of racket at impact Horizontal force Horizontal displacement Court surface Ball velocity Spin Racket characteristics Ball velocity & direction prior to impact Angle of racket face at impact Surface of ball Air Density Vertical velocity of racket head at impact Vertical force Vertical displacement Other Considerations y Observations y Evaluation y Instruction End! 3/15/2010 11 Example y Fastball pitch in baseball Roles of Models y Comprehensive models y Big picture/Framework y Observational models y A part of comprehensive model y Different emphasis szhang Microsoft PowerPoint - Qualitative Analysis.pptx
Want to see the other 11 page(s) in Qualitative Analysis?JOIN TODAY FOR FREE!